One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,6)(3,5,7,8)(9,10,15,14)(11,18,13,16)(12,20,21,17)(19,23,22,24)(25,26,31,30)(27,32,35,36)(28,33,37,39)(29,34,38,40)(3,7)(5,8)(9,11,15,13)(10,16,14,18)(12,19,21,22)(17,23,20,24)(25,27)(26,32)(28,29)(30,36)(31,35)(33,34)(37,38)(39,40)(1,2)(3,5)(4,6)(7,8)(12,21)(17,20)(19,22)(23,24)(27,35)(28,37)(32,36)(33,39) involution — undirected(1,3)(2,5)(4,7)(6,8)(9,12,15,21)(10,17,14,20)(11,19,13,22)(16,23,18,24)(25,28)(26,33)(27,29)(30,39)(31,37)(32,34)(35,38)(36,40)(1,2)(3,5)(4,6)(7,8)(9,13,15,11)(10,16,14,18)(12,22,21,19)(17,23,20,24)(25,29)(26,34)(27,28)(30,40)(31,38)(32,33)(35,37)(36,39)(9,14,15,10)(11,18,13,16)(12,17,21,20)(19,23,22,24)(25,30,31,26)(27,36,35,32)(28,33,37,39)(29,34,38,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.